This study is designed to compare the pharmacokinetics and effects of buprenorphine following administration of the sublingual tablet formulation over a dose range of 4 to 24 mg. This open label study will include twelve subjects at two sites; New England Medical Center Hospitals/Tufts University and the University of Cincinnati. The subjects will be male/female, age 21-45, within 15% of ideal body weight and use opiates. Each hospitalized patient will receive ascending single doses of 4, 8, 16 and 24 mg buprenorphine with a 10-day interval between doses. Buprenorphine is a potent pain-relieving narcotic prescription drug. A new formulation, sublingual tablet, is now being studied as a treatment for opiate addicts.